Experts Question So-Called HIV 'Cure'

"It certainly was not the complete education that I like to give to moms before initiating therapy, but considering that she had only learned that day of her own diagnosis, I knew that it would be impossible for her to understand all of the pathogenesis of HIV within the time limitations that we had," Gay said.

This was complicated by the fact that the baby's mother did not accompany the baby to the University of Mississippi Medical Center. Instead, she stayed behind at the hospital where she'd given birth.

"Physical location doesn't make it any the less important to secure her express permission to an off-label use in a circumstance where they're not certain the baby really has the disease," Caplan said. "In general, you don't want to do anything and everything you think of on the basis of an open-ended or vague consent."

Still, Caplan and Kline said they believe Gay had the patient's interests at heart, and that she had the right to deviate from standard of care.

When Did They Find the 'Cure'?

The baby continued the three-drug regimen for the next 18 months, until the baby's mother stopped taking her to clinic appointments, bringing treatment to a halt, Gay has said. It is not clear why they stopped coming to appointments or why they resumed.

The 2-year-old spent five months off treatment before returning to Gay, at which point the doctor expected to see test results showing high viral loads. Instead, the child's HIV appeared to have remained at almost undetectable levels.

"I did not expect that this baby would turn out to be a cure," Gay said in a press conference Monday. "That was a surprise to me."

Gay teamed with doctors at the University of Massachusetts Medical School and John's Hopkins Children's Center to perform more sensitive tests, and they still found almost no trace of HIV. The child has now been off treatment for 10 months with no sign of symptoms, although trace amounts of HIV DNA and RNA remain in the peripheral blood cells.

When the team of doctors announced the world's first "functional cure" of HIV at the Conference on Retroviruses and Opportunistic Infections in Atlanta, news articles appeared that night in The New York Times and the Wall Street Journal. Soon, word of a "cure" spread around the globe.

But even the researchers acknowledge that it's possible the treatment wasn't responsible for the baby's outcome.

"I'll say the early treatment most likely contributed to the outcome in this child," Persaud said during a news conference on Monday. "But whether it's the only intervention that allowed this outcome is unclear and requires further study."

Gay said in an email that "it may or may not have happened due to starting aggressive therapy very early but that is our best guess as to the cause at this point."

How Do We Know It May Be a Cure?

Fauci said the medical community has long believed that the only way to cure someone of HIV is to start treatment as early as possible, before the virus forms reservoirs or damages the immune system, which is what makes it incurable in older children and adults. But Fauci is not celebrating just yet.